This is invention relates to a system for, and a method of, treating occluded vessels (e.g. an artery) and capturing friable emboli which may break away from the lesion in the vessel during an interventional procedure. The system and method of the present invention are especially useful when performing carotid interventional procedures in order to prevent embolic debris from entering and occluding downstream blood vessels leading to the brain which, if blocked, may cause a stroke. However, the system and method of this invention can be adapted by a person of ordinary skill in the art for use in numerous other vascular interventional procedures.
In recent years, numerous procedures have been adapted for expanding blood vessels (e.g. arteries) at the positions of lesions in the blood vessels so that blood can flow through the blood vessels without obstruction from the lesions. In the process of expanding such blood vessels at the positions of the lesions, emboli may become detached from the lesions and enter the bloodstream and subsequently migrate through the patient""s vasculature to cut off or reduce the amount of oxygenated blood supplied to sensitive organs such as the brain, which may induce trauma.
Procedures have also been adapted in recent years for preventing embolic debris from flowing through the vessels in the direction of the blood flow. For example, filters have been provided for trapping the emboli. When lesions develop in the carotid artery of a patient, the placement of a filter in the patient""s vasculature can somewhat reduce the movement of emboli to blood vessels leading to the patient""s brain, thereby preventing strokes from occurring.
Such filters are usually delivered in a collapsed position through the patient""s vasculature and are then expanded once in place in the patient""s blood vessel to trap the emboli. After emboli have been trapped, the filter is collapsed and removed (with the trapped emboli) from the vessel. Unfortunately, it is possible for some of the trapped emboli to escape from the filter during the time that the filter is being collapsed and/or removed from the blood vessel. When an interventional procedure is being performed in a carotid artery, even a trace release of emboli can be damaging. For these reasons, attempts to treat lesions in the carotid arteries have been somewhat limited due to the danger presented if all of the embolic debris is not collected during the procedure.
Therefore, in light of the above, it would be desirable for a system and method which can be utilized to treat an occluded vessel and trap any emboli that may be formed during the vascular procedure. Such an apparatus and method must also prevent the emboli from escaping from the filter during the time that the filter is being collapsed and/or removed from the blood vessel (e.g. the carotid arteries). Such a device or method should be easy and safe to deploy, and be easily removed from the vasculature with little or no adverse impact or immunological response to the patient.
The present invention is directed to a system for trapping and removing emboli from a body vessel (e.g., an artery) which utilizes an expandable filtering material (e.g., an open-cell foam material) which expands within a vessel when fluid (e.g. blood) flows through the vessel. Retaining pockets formed in the expandable filtering material trap emboli which may be released in the fluid flow of the vessel. The expandable filtering material is inserted into the vessel at a particular position distal to the lesion in the direction of the fluid flow. A protective sleeve covers the expandable filtering material as the filtering material is being deployed in the vessel. An interventional device, such as an expandable member (e.g., a balloon) and a stent, is disposed in the vessel to treat the lesion. The protective sleeve is removed from the expandable filtering material when the filter is to be deployed, thereby exposing the filtering material to the fluid within the vessel which causes the filtering material to expand within the vessel. The interventional device can then be utilized to treat the lesion and expand the vessel at the lesion position.
The interventional device is thereafter collapsed and removed from the vessel. Emboli created during the interventional procedure are released into the fluid flow (e.g. bloodstream) and are trapped within the retaining pockets formed in the expandable filtering material. The protective sleeve is then disposed over the expandable filtering material to contract the material for removal from the vessel. The filtering material and the sleeve can be removed from the vessel, with the trapped emboli retained in the pockets of the filtering material.
In another embodiment, an expandable hydrogel is affixed to the end of a catheter and used in a similar manner to trap and retain emboli released into the vessel. The hydrogel material will swell or expand when subjected to a external stimulus (e.g., temperature, pH, electrical fields, magnetic fields, solvent, ionic strength, pressure, stress, light intensity and chemicals such as glucose) and will contract or shrink when the stimulus is removed. The hydrogels may be used in place of the expandable filtering material to capture embolic debris released in the vessel.
These and other advantages of the present invention will become more apparent from the following detailed description of the invention, when taken in conjunction with the accompanying exemplary drawings.